British Prime Minister Theresa May will meet ministers on Thursday to discuss Brexit, hours after her parliamentary partner threatened to withdraw its support if she accepts what it calls a "draconian solution" on offer from the European Union.

Just six months before Britain is due to leave the EU, the two sides differ on their view of the talks - the bloc says a withdrawal deal is within reach, while British officials say "significant obstacles" still lie in the way of any agreement.

They do agree on one thing - that time is running out to seal a deal to pave the way for Britain's divorce, the biggest trade and foreign policy shift for more than 40 years. As that departure date creeps closer, those wanting to influence May's approach to Brexit are stepping up their efforts.

One of the biggest hurdles is an agreement on the so-called Irish backstop to prevent the return of a hard border between the British province of Northern Ireland and EU member Ireland if there is no immediate trade deal.

A seamless border is part of the settlement which largely ended decades of violence in the province.

Neither side has indicated there has been a deal on the Irish backstop. But after meetings in Brussels, the Democratic Unionist Party, which props up the Conservative government in parliament, has issued a series of terse warnings to May.

DUP Brexit spokesman Sammy Wilson condemned what he said was the EU's offer for a backstop that would keep Britain in the customs union for an unspecified time-limited period, would exclude Northern Ireland from any new British trade deals and see checks on goods moving from mainland Britain to the province.

May's acceptance of such a proposal "would have implications not just for Brexit legislation – 50 per cent of which would not have passed without DUP support – but also for the budget, welfare reform and other domestic legislation", he said.

"She will not have DUP support regardless of whether the government tries to bribe, bully or browbeat us into accepting it," he wrote in the Daily Telegraph newspaper.

By withdrawing its support, the DUP could make it impossible for May to pass legislation through parliament, including the budget which will be voted on later this month.

MEETING

May will gather several of her ministers later on Thursday as part of routine meetings to keep her cabinet team updated on progress in Brexit talks.

The meeting takes place against growing criticism over her plans to leave the EU with some Conservative euroskeptic lawmakers saying they will vote against any deal based on her so-called "Chequers" proposal, named after her country residence.

Former prime minister John Major, whose career as leader was crushed partly by euroskeptics, said the behavior of some of those Conservatives was "an intolerable way to treat a prime minister who's in the middle of negotiations". []

But the parliamentary arithmetic is difficult for May. With the support of the DUP she commands a majority of only 13 lawmakers and needs to keep either her own party onside or attract votes from the main opposition Labour Party.

Labour leader Jeremy Corbyn has said the party will vote against any deal that does not meet its tests - something the Chequers plan does not fulfill.

And former Labour leader Tony Blair added his voice to calls for the party to vote down May's Brexit divorce deal.

"My view is this only happens if there is blockage in parliament. But if there is blockage in parliament it is a very simple argument. You say look we have been two and a bit years trying to reach an agreement that works, parliament is blocked."